System of lines

ABSTRACT

A line arrangement is provided for transmitting volume flows of fluids with a port which is assigned to a pump, a port which is assigned to an actuator and a connecting line which connects the pump to the actuator. An amplified damping effect of pulsations occurring in the line arrangement is achieved in that at least one line through which there is not a flow and which is composed at least partially of an elastic hose should branch off from the connecting line. At least one inner hose oriented axially with respect to the elastic hose is provided which has at least one free end opening axially to an axial space of the elastic hose.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a line arrangement for transmitting volumeflows of fluids, having a port which is assigned to a pump, a port whichis assigned to an actuator and a connecting line which connects the pumpto the actuator.

In such hydraulic lines, pressure pulsations may arise which exciteresonances in the lines which may not only be the cause of disruptingnoises but also of loosening of screwed connections and/or of wear.

In order to avoid these difficulties it is known to connect one or morepressure convectors to the lines through which fluids flow and which areconfigured in their volume and in their pilot pressure in such a waythat they as far as possible damp the pressure fluctuations which occur.A disadvantage with these pressure accumulators is, however, that theyhave a large volume and are thus heavy, which leads to problems in manyareas of application of line arrangements owing to the pooradaptability. In addition, these known solutions are relativelyexpensive and difficult to configure or adjust to the respectiveapplication case.

Furthermore, in order to avoid pressure pulsations in lines, it isknown, for example, from DE 35 10 267 A1, to provide a feed hose—i.e. ahose through which there is a flow and which is arranged between thepump and actuator—which is provided with an outer flexible hose part andan inner flexible hose part which is arranged coaxially in the outerhose part and extends only over part of the outer hose part. The innerhose part is connected by one of its ends to a connecting element to theouter hose part, and forms with the outer hose part an elongated,annular space. As the inner hose part does not extend over the entirelength of the outer hose part, an empty chamber is produced adjacent tothe elongated annular space. This is a region in which the fluid issurrounded only by the outer hose part. In this fluid arrangement, thefluid firstly flows through the inner hose part before it flows into theempty chamber. The inner hose part is therefore oriented with its freeend in the direction of the actuator, in other words in the flowdirection.

The known damping element acts as follows: in the described hosearrangement, pressure pulsations run firstly into the empty chamber viathe inner hose part. Some of the migrating pulsation waves willpropagate in the downstream direction in the empty chamber while otherpulsation waves will propagate in the upstream direction in theelongated annular space between the inner and outer hose parts. Thewaves which are directed upstream are deflected at the inner end wall ofthe connecting element and migrate downstream again in the annularcavity and are superimposed on the migrating pulsation waves whichemerge from the inner hose part. In this superimposition process, thewaves are partially superimposed one on the other in antiphase,resulting in a damping effect.

In some hydraulic systems, in particular in piston pumps, the dampingeffect of the described line arrangement is not sufficient to dampadequately the high emission of pulsations, and thus the high emissionof noise of the pump.

Against this background, the object of the present invention is toprovide a line arrangement for transmitting volume flows of the abovementioned type in which the damping effect is amplified.

This object is achieved with a line arrangement for transmitting volumeflows of fluids, having a port which is assigned to a pump, a port whichis assigned to an actuator, and a connecting line which connects thepump to the actuator, wherein at least one line through which there isnot a flow and which is at least partially composed of an elastic hosebranches off from the connecting line. This object is also achieved byproviding a line arrangement for transmitting volume flows of fluids,having a port which is assigned to a pump, a port which is assigned toan actuator, and a connecting line which connects the pump to theactuator, wherein at least one line which runs in parallel with theconnecting line and which is composed at least partially of an elastichose is provided.

Accordingly, the solution according to the invention is defined in thatat least one line through which there is not a flow and which branchesoff from a connecting line between pump and load is provided in the linearrangement. This line through which there is not a flow is composed atleast partially of an elastic hose and is closed off at its end facingaway from the branch. Owing to the resilience of the hose wall atincreased pressures, the line through which there is not a flow canreplace a relatively large volume and as a result compensate pressurepulsations. If such a resilient hose through which there is not a flowis connected to a hose arrangement of this generic type, the dampingeffect which is described acts on the entire line arrangement. Thearrangement according to the invention brings about considerable dampingof the pulsations, which is manifest in particular by drastically lowernoise emissions of the pump.

The elastic hose can extend over the entire length of the line throughwhich there is not a flow. However, it can extend over only part of thisline, the other part being composed, for example, of a metal tube.

The described object is also achieved by a line arrangement of thegeneric type in which at least one line which runs in parallel with theconnecting line and which is composed of an elastic hose is provided. Inthis context, a line which is guided in parallel is to be understood asa line which branches off from the connecting line at one location andjoins it again at another location downstream on the connecting line. Inthis exemplary embodiment, the fluid which is fed through the linearrangement is therefore conducted in parallel through both lines. Owingto the resilience of the hose wall, the line which is guided in parallelalso has the effect of compensating pulsations in this case, which has apositive effect on the noise emissions of the line arrangement.

The line which is guided in parallel can be composed completely or onlypartially of an elastic hose.

According to one embodiment, the lines through which there is not a flowand which are guided in parallel branch off directly at the port of theconnecting line which is assigned to the pump. In this case,particularly good degrees of damping are obtained. The branching can,however, also take place in any other region of the connecting line.

It has proven particularly advantageous if at least one inner hose witha relatively small diameter which is oriented coaxially in the outerhose is provided in the elastic hose which is arranged as a line throughwhich there is not a flow or as a parallel line. Said inner hose can beattached by one of its ends to the outer elastic hose. The connection ofthe outer and inner hoses can be made, for example, by means of a sleevewhich is arranged between the outer and inner hoses, is connected to oneend of the inner hose and is held by a sleeve-shaped clamp which isarranged around the outer hose. However, connection can also be made inany other way which is familiar to the person skilled in the art.

The free end of the inner hose which is not connected to the sleeve canbe oriented in the direction of the pump or in the direction of theclosed-off end of the elastic hose in the case of the line through whichthere is not a flow, or in the direction of the actuator in the case ofthe line which is guided in parallel. The sleeve can also be arranged inthe center of the inner hose so that the latter has two free ends, oneof which points in the direction of the pump, another in the oppositedirection.

The additional combination of lines through which there is not a flow orguided in parallel, and an interruption in the fluid column in the linearrangement which is achieved by means of additional inner hoses canreduce the noise emissions considerably over wide rotational speedranges of the pump.

A plurality of inner hoses can also be arranged in the outer elastichose. These can all be pointing in the same direction or else indifferent directions. The length of the inner hoses can also vary. Bymeans of the variants mentioned above, the degree of damping of the linearrangement according to the invention can be set precisely to therespective application cases.

It is also conceivable, in addition to the line through which there isnot a flow or the line which is guided in parallel, to make part of theconnecting line between the pump and the actuator from an elastic hose.In this hose it is also possible to provide inner hoses with relativelysmall diameters in the above-mentioned variations.

The invention will be explained in more detail below by reference to theexemplary embodiment illustrated in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of the line arrangement according to theinvention with a line section through which there is not a flow, and

FIG. 2 shows a sectional view of the line section through which there isnot a flow according to FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a line arrangement 1 according to the invention forthe hydraulic system of an active vehicle. However, the solutionaccording to the invention can also be applied in any other conceivablehydraulic system in which pulsations occur, such as for example in aservo-steering system, as a result of the transmission of pressure andvolume flows. In the case of 2, the line arrangement 1 is connected to apump (not illustrated). In the case of 3, the line arrangement 1 isconnected to an actuator (also not illustrated). The connecting line 4,which connects the pump to the actuator, is provided between the ports 2and 3. The connecting line 4 is composed partly of a metal tube 5 andalso of a resilient hose 6 which is formed from a textile-reinforced ormetal-reinforced hose which is known from the prior art.

A further line 7 branches off from the port 2. There is not a flowthrough this line 7. Line 7 is a spur line which is closed off at itsend 8 facing away from the branch 2. The spur line is also composed ofan elastic, textile-reinforced or metal-reinforced hose. Depending onthe application, the branch to the spur line can be situated between thepump and actuator at any other desired location on the connecting line 4through which there is a flow.

FIG. 2 illustrates the spur line 7 in section. The spur line 8 is closedoff at the end 8 pointing upwards in the illustration. At the endpointing downwards, the line leads to the connection 2 to the pump.

Two inner hoses 9 and 11 are arranged in the spur line 7. These twohoses have a smaller diameter than the outer hose of the spur line 7 andare arranged coaxially in it. The hose 9 is connected to the outer hose7 via the arrangement which closes off the hose end 8. In the case ofthe inner hose 11 which is arranged in the center of the outer hose 7,the connection is made via a sleeve 12 which is connected to the innerhose 11 and is arranged in the outer hose 7. The outer diameter of thesleeve 12 is matched to the inner diameter of the outer hose 7, at leastin parts. So that the sleeve 12 does not slip in the outer hose 7, asleeve-shaped clamp 13 is provided outside the outer hose 7, at theheight of the sleeve 12.

The two inner hoses 9 and 11 extend over only part of the outer spurline 7. They point in the direction of the pump with their free ends.They can also point away from the pump. However, this is not illustratedin the figures. They each form an annular space 14 and 15 with the spurline 7. An empty chamber 16 and 17 is produced in front of each of thefree ends of the inner hoses 9 and 11.

The fluid column in the dead end line 7 is interrupted by the innerhoses 9 and 11. This interruption leads to a situation in whichpulsation waves in the fluid column are divided, then cover differentdistances, are partially reflected and combined again. When thecombination occurs, the pulsation waves are superimposed on one anotherin antiphase and thus become damp.

According to a further embodiment (not illustrated), that end of theline 7 which points away from the pump is not closed off but ratherconnected at a suitable location to the connection line 4 so that theline 7 is embodied as a parallel line to the connecting line 7 and thushas a flow through it.

The solution according to the invention also works without the innerhoses 9, 11, described in conjunction with FIG. 2, as the dampingelement in the line arrangement 1. However, each entire system can beadjusted and set quite precisely by means of the inner hoses 9 and 11,in particular by means of their number, arrangement in the line 7,orientation in the line and length. Hoses corresponding to the hoses 9and 11 can also be provided in the resilient hose 6 of the connectingline 4.

1. A pipe arrangement for transmitting volume flows of a fluid,comprising: a port which is assigned to a pump, a port which is assignedto a consumer, a connecting pipe which connects the pump to theconsumer, an outer pipe having an open end and a closed end, which outerpipe is connected to the fluid at its open end, and which outer pipe isat least partially composed of an elastic hose, and an inner hose of arelatively small diameter, which (i) is oriented coaxially with respectto the outer pipe, (ii) is disposed to extend in the elastic hose of theouter pipe, and (iii) has one free end which points in the direction ofthe open end of the outer pipe and points away from the closed end ofthe outer pipe, wherein an outer diameter of the inner hose at its freeend is smaller than an inner diameter of the outer pipe to form a spacebetween the outer diameter of the inner hose and the inner diameter ofthe outer pipe.
 2. The pipe arrangement according to claim 1, whereinthe pipe, through which there is no flow of the fluid, branches offdirectly from the port, which is assigned to the pump.
 3. The pipearrangement according to claim 2, wherein a plurality of inner hoses ofdifferent lengths are arranged in the outer elastic hose of the pipethrough which there is no flow of the fluid.
 4. The pipe arrangementaccording to claim 1, wherein the pipe, through which there is no flowof the fluid, branches off from the connecting pipe.
 5. The pipearrangement according to claim 4, wherein a plurality of inner hoses ofdifferent lengths are arranged in the outer elastic hose of the pipethrough which there is no flow of the fluid.
 6. The pipe arrangementaccording to claim 1, wherein a plurality of inner hoses of differentlengths are arranged in the outer elastic hose of the pipe through whichthere is no flow of the fluid.
 7. Pipe element comprising: one port fora fluid connection to a fluid circuit, an outer pipe, which has an openend connected to the port and which has a closed end, and an inner pipe,which is arranged inside and orientated coaxially with respect to theouter pipe and which has at least one free end which points in adirection of the open end of the outer pipe and points away from theclosed end of the outer pipe, wherein at least one of the outer pipe andthe inner pipe is at least partially composed of an elastic hose, andwherein an outer diameter of the inner pipe at its free end is smallerthan an inner diameter of the outer pipe to form a space between theouter diameter of the inner pipe and the inner diameter of the outerpipe.
 8. Pipe element according to claim 7, wherein the outer pipe andthe inner pipe are at least partially composed of an elastic hose. 9.Pipe element according to claim 8, wherein the elastic hose which is atleast part of the inner pipe is arranged in the elastic hose which is atleast part of the outer hose.
 10. Pipe element according to claim 9,wherein a plurality of inner hoses of different lengths are arranged inthe outer elastic hose of the outer pipe.
 11. A pipe arrangementaccording to claim 7, wherein a plurality of said inner pipes arearranged in the outer pipe.
 12. A pipe arrangement for transmittingvolume flows of a fluid comprising: a port which is assigned to a pump,a port which is assigned to a consumer, a connecting pipe which connectsthe pump to the consumer, and a pipe element comprising: one port for afluid connection to a fluid circuit, an outer pipe, which has an openend connected to the port and which has a closed end, and an inner pipe,which is arranged inside and orientated coaxially with respect to theouter pipe and which has at least one free end which points in adirection of the open end of the outer pipe and points away from theclosed end of the outer pipe, wherein at least one of the outer pipe andthe inner pipe is at least partially composed of an elastic hose,wherein the port of the pipe element is in fluid connection with one ofthe port which is assigned to the pump, the port which is assigned tothe consumer and the connection pipe, and wherein an outer diameter ofthe inner pipe at its free end is smaller than an inner diameter of theouter pipe to form a space between the outer diameter of the inner pipeand the inner diameter of the outer pipe.
 13. A pipe arrangementaccording to claim 12, wherein the outer pipe and the inner pipe are atleast partially composed of an elastic hose.
 14. A pipe arrangementaccording to claim 13, wherein the elastic hose which is at least partof the inner pipe is arranged in the elastic hose which is at least partof the outer hose.
 15. A pipe arrangement according to claim 14, whereina plurality of inner hoses of different lengths are arranged in theouter elastic hose of the outer pipe.